According to their working principles, HVDC converter technologies today can be distinguished as linecommutated or current sourced converter technologies (LCC or CSC) and voltage sourced converter (VSC). LCC uses halfcontrollable thyristors as switching devices, whereas VSC uses fully controllable devices, such as insulated gate bipolar transistors (IGBT), gate turn-off thyristor (GTO), or catecommutated thyristor (IGCT) as switching devices.